ABSTRACT
The paper presents a review of three of the studies undertaken by the authors regarding the implications of the fretting
phenomenon that can manifest in a total hip prosthesis, on its stability. Experimental investigations have been made on
Ti6Al4V / UHMWPE prostheses with cemented stem Failure to fix the cemented stem of the prosthesis occurred at 2450000
cycles, after which visual inspection was done and photographic recordings were made. Two different conditions were
considered for the normal force N between the contact surfaces: constant or proportional to the axial force P. Determination of
the stresses induced in the fretting process required the preliminary characterization of the relationship between the friction
force F and the axial force P produced during the loading cycles. Hereafter, experimental studies were carried out to detect the
early stage when fretting wear of the Ti-6Al-4V alloy, used for the hip prostheses, appears. Wear is a critical aspect for
estimating the fretting fatigue. It was taken into account the unanimous finding that the surface roughness of the testing
sample has a significant influence on the occurrence and evolution of the fretting scar. Studies were realized on samples of
special shape presented in this paper.
Keywords: hip implant, fretting corrosion, fretting fatigue, PMMA, Ti6Al4V